Anti-armor warhead assembly

ABSTRACT

An anti-armor warhead assembly includes an open-ended cylindrical warhead se defined by a first section, a second section and a third section. The first section has a constant inside diameter D 1 . The second section has a constant inside diameter D 2  and connects the first section and the third section. The third section is defined by an inside diameter D 3 . The relationship between the diameters is such that D 1  &lt;D 3  ≦D 2 . A hollow conically shaped charge liner is axially aligned and fitted within the warhead case. Explosive material fills the first section of the warhead case about an outwardly facing surface of the charge liner. A retaining ring fitted on the third section retains the charge liner and the explosive material in the first section. An end cap fitted to the first section has an initiator coupler formed therein for housing a primer charge used to detonate the explosive material.

ORIGIN OF THE INVENTION

The invention described herein was made in the performance of officialduties by an employee of the Department of the Navy and may bemanufactured, used, licensed by or for the Government for anygovernmental purpose without payment of any royalties thereon.

FIELD OF THE INVENTION

The invention relates generally to warhead assemblies, and moreparticularly to an anti-armor warhead assembly that can be loaded witheither cast or pressed explosive material.

BACKGROUND OF THE INVENTION

Anti-armor projectiles are known in the art and include a variety ofdesigns. Typically, the projectile's warhead assembly includes a shapedcharge of explosive. The warhead assembly is generally designed to beloaded with an explosive material that is either cast directly in thewarhead assembly or is a pressed, i.e., solid, explosive material thatis fitted into the warhead assembly. However, it is desirable for awarhead assembly to be loadable with either a cast or pressed explosivematerial. In this way, the best explosive material for a particularapplication can be selected. Furthermore, as the U.S. military strivesto cut costs via versatility in design, it is best to have a universalwarhead assembly in terms of being loaded with either a cast or pressedexplosive material.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide ananti-armor assembly that can be loaded with either a cast or pressedexplosive material.

Other objects and advantages of the present invention will become moreobvious hereinafter in the specification and drawings.

In accordance with the present invention, an anti-armor warhead assemblyincludes an open-ended cylindrical warhead case for the structuralsupport of the warhead assembly in flight. The warhead case defined by afirst section, a second section and a third section. The first sectionhas a constant inside diameter D₁. The second section has a constantinside diameter D₂ and connects the first section and the third section.The third section is defined by inwardly facing threads that present aninside diameter D₃. The relationship between the diameters is such thatD₁ <D₃ ≦D₂. A hollow conically shaped charge liner is axially alignedand fitted within the warhead case. The charge liner has a closed apexand an open base, and further defines an inwardly facing surface and anoutwardly facing surface. Explosive material fills the first section ofthe warhead case about the outwardly facing surface of the charge liner.A retaining ring, threadably engaged with the inwardly facing threads ofthe third section, retains the charge liner and the explosive materialin the first section. An end cap, fitted to the first section, has aninitiator coupler formed therein for housing a primer charge used todetonate the explosive material. The initiator coupler is in axialalignment with the charge liner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side, cross-sectional view of the anti-armor warheadassembly according to the present invention; and

FIG. 2 is a side, cross-sectional view of the warhead assembly of thepresent invention with its end caps adapted for installation in theMERLIN anti-armor mortar projectile.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIG. 1,anti-armor warhead assembly 10 is shown in cross-section. Assembly 10includes warhead case body 12, charge liner 14, explosive material 16,retaining ring 18 and end cap 20.

Warhead case body 12 forms the structural support for explosive material16 and must be constructed to withstand both launch and in-flight forcesexperienced by assembly 10 in its particular application. Typically,warhead case body 12 is made from a high-strength steel, plastic orcomposite material.

In terms of the present invention, warhead case body 12 is a hollowcylindrical tube that is defined by sections 120, 121 and 122. Section120 extends from one open end of warhead case body 12 (that mates withend cap 20) to section 121. Thus, section 122 extends from the otheropen end of warhead case body 12 (that mates with end cap 18) to section121. Section 121 extends between sections 120 and 122.

Section 120 presents a constant inside diameter D₁ along its smoothinterior surface. Threads 124 face outwardly from one end of section 120for threaded engagement with inwardly facing threads 200 of end cap 20.Along section 122, threads 126 face inwardly and present an insidediameter D₃ that is slightly larger than inside diameter D₁ for reasonsthat will be discussed further below. Threads 126 engage with outwardlyfacing threads 180 on retaining ring 18. Section 121 is essentially aninwardly facing annular groove machined into warhead case body 12 forreceiving annular lip 140 (if one is present) of charge liner 14 as willbe explained further below. Section 121 presents an inside diameter D₂that can be equal to or slightly greater than inside diameter D₃.

Charge liner 14 is a hollow, conically shaped material that distorts toform a (shaped charge assembly) jet a when explosive material 16 isdetonated as is well understood by one skilled in the art of shapedcharge assemblies. Choice of materials for charge liner 14 is dependentupon what the warhead is intended to defeat and can be metal, glass,ceramic or any other solid material that distorts to form a jet whenexplosive material 16 is detonated. For anti-armor purposes, copper orother high-density metals are usually selected for charge liner 14.

Charge liner 14 is defined by a closed apex 141 and an open basedesignated by dashed line 142. Charge liner 14, when fitted in warheadcase body 12, has its central longitudinal axis 143 axially alignedwithin section 120 of warhead case body 12. Annular lip 140 at open base142 fits in the annular groove formed by section 121 of warhead casebody 12. As will be explained further below, annular lip 140 must bepresent if explosive material is to be cast in warhead case body 12while annular lip 140 can be present if explosive material is a pressedexplosive.

As is understood in the art, when explosive material 16 is detonated, aspherical shock wave propagates outward at high velocity from the pointof initiation. As the shock wave collides with charge liner 14, theconical shape of charge liner 14 collapses such that closed apex 141moves along central longitudinal axis 143 towards and through open base142. In other words, closed apex 141 becomes the faster moving tip of ajet while open base 142 becomes the slower moving tail of the jet. Theresulting jet exits assembly 10 through retaining ring 18.

Explosive material 16 is any cast or pressed explosive that, in mostapplications, is selected to be as insensitive as possible, i.e.,remaining inert until detonation is initiated as planned. Commonly usedcast explosive materials are U.S. military supply explosives PBXN-110,OCTOL and PBXC126. Commonly used pressed explosive materials are U.S.military supply explosives LX-14, PBXW-11 and PBXN-9. For all suchexplosive materials, explosive material 16 fills the entire warhead casebody 12 between the inside walls of section 120 and outwardly facingsurface 144 of charge liner 14.

Retaining ring 18 is a cylindrical ring having open end 181 and open end182. Retaining ring 18 is typically made from the same material as thatof warhead case body 12 since it will be subject to high G-loads uponlaunch of assembly 10. Outwardly facing threads 180 starting at open end181 engage with threads 126 of section 122 of warhead case body 12. Openend 181 of retaining ring 18 comes to rest against annular lip 140 (ifpresent), or within section 121 if charge liner 14 has no such annularlip, in order to retain charge liner 14 and explosive material 16 inplace in section 120. Retaining ring 18 at open end 182 can be adaptedto fit a particular projectile application as will be explained furtherbelow. So as not to interfere with the tail of the jet formed by chargeliner 14 at detonation, inside surface 183 of retaining ring 18 tapersoutward so that open end 181 is sized to match open base 142.

End cap 20, typically made from the same material as that of warheadcase body 12, is a cylindrical end cap having cylindrical flange 201extending from end cap housing 202. Inwardly facing threads 200 formedalong cylindrical flange 201 engage with threads 124 of section 120. Endcap housing 202 is machined to define initiator coupler 204 for holdingprimer charge 205 which detonates explosive material 16 at a timedetermined by the particular application. End cap housing 202 is flatalong inner surface 203 thereof to be in flush contact with explosivematerial 16 to insure that primer charge 205 only contacts explosivematerial 16 where defined by initiator coupler 204. Further, end caphousing 202 can be adapted to fit a particular projectile application.

The design of initiator coupler 204 is typically a precision initiatorcoupler for causing detonation of explosive material in such a way thatthe resulting shock wave is symmetric about central longitudinal axis143. In the preferred embodiment, initiator coupler 204 is divided intothree sections, namely, initiating section 204a, concentrating column204b and detonation section 204c, all of which are symmetric aboutcentral longitudinal axis 143. Briefly, initiating section 204a receivesoutput from a fuzing device (not shown) to start an explosive reactionof primer charge 205. Concentrating column 204b transfers the initiatedexplosive reaction to detonation section 204c in a concentrated fashion.Detonation section 204c transfers the explosive reaction to explosivematerial 16.

To load assembly 10 with a castable-type explosive material, chargeliner 14 having annular lip 140 is passed through sections 122 and 121where it is fitted into warhead case body 12 so that annular lip 140comes to rest in section 121. Retaining ring 18 is screwed into section122 until that portion of retaining ring 18 at open end 181 seatsagainst annular lip 140 thereby holding charge liner 14 in place.Explosive material 16 is poured into warhead case body 12 aboutoutwardly facing surface 144 of charge liner 14. End cap 20 is screwedinto section 120 so that inner surface 203 is flush with explosivematerial 16.

If explosive material 16 is of the pressed type, explosive material 16is machined to its ultimate shape (i.e., its exterior diameter sized tofit into section 120 and its interior conical portion sized/shaped tomate with outwardly facing surface 144 of charge liner 14) prior toinstallation into warhead case body 12. The machined explosive materialwith charge liner 14 therein is positioned in warhead case body 12through section 120. To facilitate such installation, charge liner 14has no annular lip 140 since the inside diameter D₁ is less than theoutside diameter presented by such annular lip. (Note that if chargeliner 14 is installed via section 122 after explosive material has beenpositioned, annular lip 140 could still be present on charge liner 14.However, this may jeopardize the centering alignment of charge liner 14in explosive material 16 since charge liner 14 would be positioned bymeans of retaining ring 18 cooperating with annular lip 140.) Retainingring 18 and end cap 20 are then screwed onto warhead case body 12 asdescribed above.

As noted above, retaining ring 18 and end cap 20 can easily be adaptedto fit a particular projectile. For example, as shown in FIG. 2,anti-armor warhead assembly 100 is shown for use with the MERLINterminally guided anti-armor mortar projectile produced by BritishAerospace of Great Britain. The elements in common with warhead assembly10 are shown with like reference numerals. End cap 20 includesrearwardly extending circumferential flange 206 forming an interferencefit with the aft end of the existing MERLIN round (not shown). Retainingring 18 has forwardly extending circumferential flange 184 for seatingin the forward end of the existing MERLIN round (not shown).

Although the invention has been described relative to a specificembodiment thereof, there are numerous variations and modifications thatwill be readily apparent to those skilled in the art in light of theabove teachings. It is therefore to be understood that, within the scopeof the appended claims, the invention may be practiced other than asspecifically described.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. An anti-armor warhead assembly, comprising:anopen-ended cylindrical warhead case for structurally supporting saidwarhead assembly in flight, said warhead case defined by a firstsection, a second section and a third section, said first section havinga constant inside diameter D₁, said second section having a constantinside diameter D₂, said second section further being between andconnecting said first section and said third section, and said thirdsection defined by inwardly facing threads presenting an inside diameterD₃, wherein D₁ <D₃ ≦D₂ ; a hollow conically shaped charge liner axiallyaligned and fitted within said warhead case, said charge liner having aclosed apex and an open base opposite said closed apex, said chargeliner further defining an inwardly facing surface and an outwardlyfacing surface; explosive material filling said first section of saidwarhead case about said outwardly facing surface of said charge liner; aretaining ring threadably engaging said inwardly facing threads of saidthird section for retaining said charge liner and said explosivematerial in said first section; and an end cap fitted to said firstsection, said end cap having an initiator coupler formed therein forhousing a primer charge used to detonate said explosive material, saidinitiator coupler being in axial alignment with said charge liner.
 2. Ananti-armor warhead assembly as in claim 1 wherein said open base of saidcharge liner defines an annular lip extending radially outward from saidcharge liner to engage said second section of said warhead case.